/*
 *  unmount() - Unmount a File System
 *
 *  This routine is not defined in the POSIX 1003.1b standard but
 *  in some form is supported on most UNIX and POSIX systems.  This
 *  routine is necessary to mount instantiations of a file system
 *  into the file system name space.
 *
 *  COPYRIGHT (c) 1989-2010.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.com/license/LICENSE.
 *
 *  $Id$
 */

#if HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include <rtems/libio_.h>
#include <rtems/seterr.h>
#include <rtems/chain.h>

static bool is_fs_below_mount_point(
  const rtems_filesystem_mount_table_entry_t *mt_entry,
  void *arg
)
{
  return arg == mt_entry->mt_point_node.mt_entry;
}

/*
 *  unmount
 *
 *  This routine will attempt to unmount the file system that has been
 *  is mounted a path.  If the operation is successful, 0 will
 *  be returned to the calling routine.  Otherwise, 1 will be returned.
 */

int unmount(
  const char *path
)
{
  rtems_filesystem_location_info_t      loc;
  rtems_filesystem_location_info_t     *fs_root_loc;
  rtems_filesystem_location_info_t     *fs_mount_loc;
  rtems_filesystem_mount_table_entry_t *mt_entry;

  /*
   *  Get
   *    The root node of the mounted filesytem.
   *    The node for the directory that the fileystem is mounted on.
   *    The mount entry that is being refered to.
   */

  if ( rtems_filesystem_evaluate_path( path, strlen( path ), 0x0, &loc, true ) )
    return -1;

  mt_entry     = loc.mt_entry;
  fs_mount_loc = &mt_entry->mt_point_node;
  fs_root_loc  = &mt_entry->mt_fs_root;

  /*
   * Verify this is the root node for the file system to be unmounted.
   */

  if ( fs_root_loc->node_access != loc.node_access ){
    rtems_filesystem_freenode( &loc );
    rtems_set_errno_and_return_minus_one( EACCES );
  }

  /*
   * Free the loc node and just use the nodes from the mt_entry .
   */

  rtems_filesystem_freenode( &loc );

  /*
   *  Verify the current node is not in this filesystem.
   *  XXX - Joel I have a question here wasn't code added
   *        that made the current node thread based instead
   *        of system based?  I thought it was but it doesn't
   *        look like it in this version.
   */

  if ( rtems_filesystem_current.mt_entry == mt_entry )
    rtems_set_errno_and_return_minus_one( EBUSY );

  /*
   *  Verify there are no file systems below the path specified
   */

  if ( rtems_filesystem_mount_iterate( is_fs_below_mount_point,
                                       fs_root_loc->mt_entry ) )
    rtems_set_errno_and_return_minus_one( EBUSY );

  /*
   *  Run the file descriptor table to determine if there are any file
   *  descriptors that are currently active and reference nodes in the
   *  file system that we are trying to unmount
   */

  if ( rtems_libio_is_open_files_in_fs( mt_entry ) == 1 )
    rtems_set_errno_and_return_minus_one( EBUSY );

  /*
   * Allow the file system being unmounted on to do its cleanup.
   * If it fails it will set the errno to the approprate value
   * and the fileystem will not be modified.
   */

  if (( fs_mount_loc->ops->unmount_h )( mt_entry ) != 0 )
    return -1;

  /*
   *  Allow the mounted filesystem to unmark the use of the root node.
   *
   *  Run the unmount function for the subordinate file system.
   *
   *  If we fail to unmount the filesystem remount it on the base filesystems
   *  directory node.
   *
   *  NOTE:  Fatal error is called in a case which should never happen
   *         This was response was questionable but the best we could
   *         come up with.
   */

  if ((fs_root_loc->ops->fsunmount_me_h )( mt_entry ) != 0){
    if (( fs_mount_loc->ops->mount_h )( mt_entry ) != 0 )
      rtems_fatal_error_occurred( 0 );
    return -1;
  }

  /*
   *  Extract the mount table entry from the chain
   */

  rtems_libio_lock();
  rtems_chain_extract( &mt_entry->Node );
  rtems_libio_unlock();

  /*
   *  Free the memory node that was allocated in mount
   *  Free the memory associated with the extracted mount table entry.
   */

  rtems_filesystem_freenode( fs_mount_loc );
  free( mt_entry );

  return 0;
}